I think it was a very bad idea ever to ban "grey imports". I regret that it's still the case in the EU.

And if this ruling had gone the other way, far more than grey imports would have been banned.

Any item containing any copyright material that was manufactured outside the US would have become illegal to resell in the US. Even if bought there. A publisher would have been able to print books in China for sale in the US market, and then forbidden the resale of those books.